Air spring



AIR SPRING J. J. MGELROY Filed Deo. 19. 1921 een Oct. 12 1926.

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UNITED As'rarr. s

JOHN J. MonLnoY, or Naw HAVEN, ooNNnc'rrour, nssIcNOa ro 'rHnwEsrntoHoUsn ma srmNe OOMPANY, orNnw HAVEN, coNNEoricU'r, CORPORATION orPENN- SYLVANIA..

.AIB SPRING.

Application led December 19, 1921. Serial 170.523,898.

This invention relates to hydro-pneumatic devices of the type set forthby Letters Patent No.A 1,036,043 issued to George Westinghouse on August20, 1912.

In the present application las in said patent, the invention is embodiedin a fluid compression device adaptedfor use as a compression springbroadl applicable in any relation where two bo ies are so associatedthat resilient support of one is desirable,

v and a general object in view in this application as in said patent,iswto embodyV the principle of yresilient support 'by an'felasticcompression medium such as air in a oommercially practical self-contanedairtight compression device adapted to serve all of the purposes andfunctions of a'sprmg.

This invention also resembles the device of said patent in so far as afluid tight joint -between the sliding surfaces of thedevice ismaintained by means of a liquid seal.

This invention also resembles the `device of Patent No. 1,179,253 issuedto George Westinghouse on April 11, 1916, in that succes- 95 siveannular packings for the sliding joint between the plunger and thecylinder are utilized and a ump having its intake .connected up to t espace between said Apackings is utilized for withdrawing sealing liquidfrom between the packings and for returning it to the load supportingcushion chamber.

This invention also resemblesthat of Patent No. 1,146,335 issude toRichard Liebau on June 13, 1915, in that the pump for transferringliquid from the sliding 'oint to the load supporting cushion chamber asone of its elements, carried b one of the ,rela.=

' tively movable members Orming a part of the cushion chamber, while theother pump member is mechanicall connected to the other relatively movabe member forming the cushion chamber. 1

. According to the present invention, which is, broadly applicablefor.use as a spring for motor vehicles (which hereinafter without anyideav of limi be referred to as an air ring) a pump of such character isutilized t at under no conditions of operation will air be forced,thereby into the variable volume cushion ch ber of the air spring. j

A further object of invention is to provide aneieetive rabo d checksthat 0;-

` g the' invention willV treme extension movements of the air springwill be cushioned without shock or jar.

A still further object is to provide a relai tively cheap, simple air sring of the direct acting ty as distinguiied from the devices of t ose(patents in which the sealing liquid is cause to surge through aconstriction' in the plunger head during the extenring.

A still further object is toprovide' a sim le, rugged air springconstruction in which a flexible boot may be readily utili'zed forprotecting the exposed sliding surfaces from ust, etc.

. The single figure of the drawings is a sectional elevation of a frontair -springembodyin this invention.

The evice consists of a suitablelength of tubing 3, to the upper end ofVwhich a dome shaped head 4 isthreaded and to the lower .sion andcompression movements of the air.A

end of which a cup-shaped casting 5 is,

threaded.

A pliston or plunger carrying two annular eupaped packings 6 and 7 isarranged to slide within tubing 3 and divi-des the interior of the airspring into a variable volume load supporting cushion chamber 8 and arebound or recoil check chamber 9.

A piston rod 10, carries the piston o`rV plunger and projects throughbottom 11 of the air spring and by means of a suitable connector 12 isconnected to the front end of one of the front leaf springs 13 ofthevehicle (in the case'offront springs) while cup-shaped member 5 whichforms the lower portion of the air spring is formed for suitableconnectionby means of bolts 14 to a bracket 15 which, in turn is formedfor, attachment to one front horn 16 of the vehicle frame. i

The piston of the r'air spring preferably consists of a lower annularnut or base 17 threaded onto the piston rod and an upper annular nut orfollower 18 threaded onto the upper end of the piston rod. These twonuts 17 and 18 form supports for the cup packings 6 and 7 and theirouter periphroo cries are preferably finished so as to form held inplace on nut 17 by means of an an- .nular washer 19 and a tubularretainer 20,

vhicliis held in plm by cylindrical nut 18.

The free edge of each of the cupped ackings is pressed against the innerwall o cylinder 3 by means of a cone expander 21 and a helical spring22. Cupped packing 7 4is held in place on annular iiange 23 of annularnut 18 by means of an annular washer 24 and nut 25. Nut 25 is threadedonto the threaded external surface of annular nut 18 and is formed witha relatively long cylindrical bearing surface 26.

Piston rod' 10 is provided with an upper extension 27 and this, as wellas a portionv of the rod below the same is drilled to form a pump barrel28. A valve seat 29 for a ball valve 30 is formed in the bottom of thepump barrel and a duct or channel 31 connects the pump barrel with thespace 32 inside of tubular packing retainer 20. This retainer isprovided with a number of oil holes 33 near its upper edge and the spacebetween this tubular retainer and kthe wall of cylinder 3 below holes 33serves as' an oil retaining chamber for maintaining a constant oil sealfor the free edge of cup packlng 6.

Oil ducts 34 extend through flange 26 of the piston. A pin 35 extendsthrough the piston rod above ball valve 30 and retains the valve at thelower end of the pump barrel.

A tubular piston 36 secured to head 4 of the device is reciprocablewithin the pump barrel and this piston at its upper end is slightlyenlargedto form a valve housing having a valve seat 37 for a ball valve38 which is retained in place by means of a pin 39.

The pump piston above ball valve 38 is provided with a hole 40 throughwhichthe oil forced up past the valve 38 will flow into the cushionchamber 8 of the air spring.

The upper end of the tubular piston is provided with an annular ange 41which is held in contact with an annular lip surrounding the centralopening in the dome shaped top member 4. The upper end of the piston 36has a loose t with the inner periphery of lip 42 so that the piston 36is self-centering with relation to pump barrel 28. The piston 36 issecurely held in place longitudinally by means of threaded nut 43 whichbears on the top of flange 41. Nut 43 is drilled and tapped to receivean ordinary tire valve 44.

lianged bushing 45 formed from suitable bearing metal is placed withinthe central opening of bottom member 11 and serves as a bearing for thepiston rod 10.

An annular buffer., 46 formed of some suitable soft material looselysurrounds piston rod 10 and rests on Y, the bottom vof recoil chamber 9.A flexible boot 47 at its upper end is secured: to a lower annularprojection on the bottom member of the spring bymeansof a retaining ringorwire 48 while' the lower end of the boot is secured to an upwardlyextending annular flange 49 of connector 12 by means of a retaining ringor wire 50.

A dust guard 51 preferably formed of sheet metal is connected to thelower end of bottom member 5 and near its top is pierced to receive anoiling plug 54 which is threaded within a tapped hole near the bottom ofthe device. An oil duct 52 leads from this oiling plug through bushing45 to the piston rod and a drain duct 53 leads from the bottom of recoilchamber 9 and is normally closed by oiling plug 54.

Normally' the cushion chamber 8 will be filled with suitable oil to thelevel marked X and during operation of the air spring oil which leakspast packing 7 will collect Within the annular chamber above packing 6.The surplus which Hows through openings 33 in the tubular packingretainer 20 will flow into annular chamber 32 and from there will passto the inlet duct 31 of the oil pump. Upon extension and compressionmovements of the air spring, this oil will be pumped back to the cushionchamber 8 of the device.

It will be understood that the device will be initially charged with therequired amount of air under pressure through valve -44. The air pumpedthrough valve 44 will iow into the cushion chamber 8 of the devicethrough opening 40 in the pump piston above the outlet valve 38.

The pump, on account of its tubular piston 36 with its outlet valvelocated at its top is of such a low volumetric. efficiency that no airwill be forced into the cushion chamber 8 during any operatingconditions that the air spring may be subjected to.

It Will be understood that if desired instead of having chamber 9 belowthe piston substantially air-tight for the purpose of forming a recoilcheck, a conical shaped helical spring having its base resting on thebottom of the cylinder and its apex terminating short of the piston withthe piston in mid position, may be utilized as a re-` coil check.

Oil ducts 34 render any oil in cushion chamber 8 available as sealingliquid for high pressure packin 7.

Having thus descried my invention, what I claim is 1. In a vehicle airkspring, a cylinder, a piston dividing the cylinder into a cushionchamber on one side and a rebound check chamber on the other side, a rodextending from said piston through the bottom of said cylinder, spacedpackings for the joint between said piston and cylinder, a liquidcollecting chamber in the s ace between said packin a pump barre carriedby said rod ansa hollow plunger connected to said cylinder and having adischarge valve located adjacent its end farthest removed from saidpiston. v

2. In a vehicle air spring, relatively movable members forming twoclosed chambers of variable volumetric capacity and the pressures inwhich act in opposition, spaced packings Jfor the sliding joint betweensaid members and a pump connected to and positively operated by themovement of said members for transferring liquid internally from thespace between said packings and being so constructed as to be incapableof pumping air during the normal operation of said spring.

3. In a vehlcle air spring, a cylinder provided with top and bottommembers, a piston, a rod extending from said piston said cylinder andthrough the bottom of with said piston dividing the cylinder into anairtight cushion chamber and a relatively tight rebound check chamber,successive annular packings for said piston and a pumpl having oneelement carried by said cylinder and the other element carried by saidpiston and having its inlet in the space'between said packings and itsoutlet passing through said piston.

4. In a vehicle air spring, a cylinder, top

and bottom members for said cylinder, a`

piston slidable within said cylinder, a rod extending from said pistonthrough the bottom member and with said piston dividin said cylinderinto an upper cushion cham er and a lower rebound check chamber,successive annular ackin s carried by said piston between sai cham ers,a pump barrel carried by said piston, plunger carried by the top member,a valved inlet passage terminating in the space between said packn tosaid pump barrel, a pump outlet va ve at the top of said plunger, anopening in said plunger above said outlet valve and a valved air inletcommunicating with the top of said plunger.

5. In a vehicle air spring, relatively movable members forming anair-tight cushion chamber and a relativelyA tight rebound check chamber,said chambers being of variable volumetric capacity and the pressure inwhlch act in opposition, spaced packings for the sliding jolnt betweenthe said members and enclosing a liquid collecting chamber on the lowpressure side of said and a pump operated by the movement of saidmembers for transferring liquid internally from the low pressure side ofsaid sliding joint to the high pressure side thereof.

In `testimony whereof, I have hereunto subscribed my name this 5th dayof December, 1921.

JOHN J. MCELROY.

sliding oint,

a hollow pump

